INDICATION: Thrombocytopenia due to chronic immune (idiopathic) thrombocytopenic purpura (ITP) in adults who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy.

PHARMACOLOGY: Eltrombopag is an orally active thrombopoietin (TPO) receptor agonist that stimulates the proliferation and differentiation of megakaryocytes from bone marrow progenitor cells. It works by interacting with the thrombopoietin receptor to cause increased platelet production.

CLINICAL TRIALS: Two studies were conducted to evaluate the safety and efficacy of eltrombopag in treating chronic ITP. Patients who had completed at least one prior ITP therapy and who had a platelet count of <30x109/L were randomized to either eltrombopag or placebo daily for up to 6 weeks, then 6 weeks off therapy. The primary endpoint was the response rate, defined as a shift from baseline platelet count to >50 x 109/L at any time during treatment. The groups given eltrombopag 50mg/day had response rates of 59% and 70% in Studies 1 and 2, respectively; for those given placebo, the rates were 16% and 11%.